Intra-operative laser-induced photodynamic therapy in the treatment of experimental hepatic tumours

Objective: To examine the effect of photodynamic therapy (PDT) on experimental liver tumours in rats. Design: An experimental liver tumour model was used. Each of a group of rats had two turnours simultaneously inoculated into its liver. The tumour located in the left hepatic lobe was used for PDT, and the other one, in the median lobe, as a control. The haem precursor δ-amino laevulinic acid (ALA), at a dose of 30 mg/kg body weight, was injected 60 min before laser irradiation. Rats in group I received ALA through a femoral vein. Those in group II received ALA through the portal vein. Group III had an injection of ALA solution through the portal vein plus hepatic inflow occlusion. Three and 6 days after the treatment, the rats were killed, and the tumours were measured, and ultrastructural changes were examined using scanning electron microscopy. Setting: Lund University Medical Laser Centre, Lund, Sweden. Results: The mean tumour volume of the treated tumours increased by factors of 1.9, 1.5 and 1.7 in groups I, II and III, respectively, compared with the pretreatment baseline value. However, the mean tumour volume in the control tumours increased by factors of 9.5, 4.3 and 4.8 in the respective groups. Under the light microscope, marked necrosis of the treated tumour and the surrounding liver tissue was observed. Scanning electron microscopy revealed heavy damage to the cells and vessels in the treated tumour. Conclusion: PDT with ALA is an effective treatment modality for rat liver tumours.